the Uni Paint PX-30 is the ideal choice

This mini marker comes filled with black alcohol based Hard2Buff ink and is easy to pop right in your pocket

keeps the leads stable while still allowing some flexibility

you'll also find an eraser at the top (which is also refillable)

caran dache sketcher non photo blue pencil 2 pack Tombow ABT Dual Brush-Pen the Uni Paint PX-30 isThis pencil is designed for artists, illustrators, and designers who need clean, erasable lines that wont interfere with later stages of their work. The included pencil tip eraser makes corrections simple without compromising the quality of your sketch. Because the soft blue line does not appear in black and white reproductions, its ideal for comics, animation, fashion sketches, architectural drawings, and other artistic fields. Inking can be done